Intensive inbreeding and line-breeding of purebred dogs in the United States has resulted in nurmerous breeds developing hereditary cataracts of both the congenital and developmental forms. We propose to study hereditary, developmental cataracts in the Cocker Spaniel dog. Cataracts in the Cocker Spaniel dog begin in the posterior subcapsular area and appear to be inherited as an autosomal recessive trait. These spontaneously developing hereditary lenticular changes provide a model to study the ultrastructural, ionic and enzymatic changes in the lens and to compare these abnormalities to spontaneously developing cataract formation in man. This research is designed to study in-depth spontaneous occurring heredo-familial cataracts in Cocker Spaniel dogs. The study will utilize various parameters including: (1) ultrastructural study of the lens epithelium and lens cells in normal and abnormal lenses; (2) glutathione concentration and enzyme activity levels of the glutathione metabolic pathway in the normal lens and in the lens with developing cataracts; (3) to study the lipids of normal and cataractous lenses; (4) to perform in vitro studies designed to relate phospholipid composition to membrane permeability and to reactivation of delipidized ATPase; (5) to measure ATPase activity in the lenses used for lipid studies; (6) to measure cation levels and water content of both normal lenses and lenses with developing cataracts.